Honestly none of the champs are really long lasting and remarkable. You have guys like Islam and Pereira, but it's tons of new champs and the guard is changing. I get why it doesn't feel as "big" as it used to. I think its a valley right now until the divisions shake out. Also inactivity of any of the top guys who are content waiting 6months to a year for a free title shot. UFC needs to pull out the whips and make it normal to fight 3x a year, it's not hard.
I remember how people used to bitch that GSP only fought twice a year when he was champ...
Then we got to Khabib fighting once a year, lol
Anyways, I like the point you bring up.
Also consider: Khabib retired in his prime after just 3 defenses
Cejudo vacated in his prime
Jones vacated the LHW belt in his prime
Ngannou left the UFC in his prime
I understand that losing is part of the sport... but it's the politics of it that's really harming the sport too.
The Jon Jones LHW dynasty came to an end due to politics. Dana White threw Jones under the bus in public because Jones was asking for more money to move to HW.
Similarly, with Ngannou they refused to pay the man his worth and once again threw him under the bus...
Conor held out for years due to politics as well. There seems to be a lot of Dana White affecting the sport, and top tier champs. Khabib wanted to fight GSP... Dana said no.